But don’t worry, you can still get updates on current projects, find agency announcements, participate in outreach and surveys, or ask us questions on our regular Twitter channel @seattleDOT. Here’s a snapshot of our three Twitter channels:

This week, the public has been asking us if the new Adaptive System we adopted on Mercer Avenue last Spring has helped ease traffic backups. The new smart technology system collects traffic data in real time, coordinating traffic signals along the corridor to move cars onto I-5 as quickly as possible so we can reduce travel time and increase reliability.

We’ve successfully decreased the time drivers sit in traffic along the corridor. For example, before installing our new system, wait times during the height of work-week rush hour backups (between 6 and 7 PM) was approximately 34 minutes. Yes, you read that correctly, during the busiest weekday peak, travelers sat in traffic for 34 minutes.

Today, during that exact same time frame, the wait is down to 17 minutes.

Is this perfect? Not by a longshot, but cutting the wait in half is a notable improvement.

More Mercer traffic improvement data:

It’s not just the worst times that have dropped under our new adaptive traffic tech. Across the board, the statistics show improvement. Below is a snapshot of the average time drivers spent in traffic pre- and post-Mercer adaptive technology:

Before the Mercer Adaptive Signal:

5 PM weekday – 14 mins.

6 PM weekday – 16 mins.

7 PM weekday – 18 mins.

After the Mercer Adaptive Signal:

5 PM weekday – 04 mins.

6 PM weekday – 06 mins.

7 PM weekday – 07 mins.

Totally recognizing that drivers would prefer to spend zero time in traffic, and would rather be at home than stuck in their cars listening to Throwback Thursday jams or news hour updates on Trump’s tweets, we remain committed to improving traffic times and reducing congestion even more. The reality is the corridor sees a high-volume of cars daily, during peak times, and we are constantly monitoring the situation.

What about pedestrian signals and walk times?

Pedestrians are also a factor in the Mercer equation. And they too have pressed us with questions. Pedestrians say the walk cycles for crossing Mercer are too short. Now, as for walk cycles, it’s important to note that East Mercer has high vehicle volumes, and in fact it’s much higher than the West side of the corridor. We heard pedestrians’ concerns about short walk times loud and clear, and recently adjusted pedestrian walk times making the following, significant adjustments.

Pedestrians should know though, that extended walk times mean fewer walk cycles. We are still working to find the best balance for pedestrians as we sync walk cycles with the car signaling to keep reducing traffic wait times.

SDOT City Traffic Engineer, Dongho Chang, explains bicycle and transit markings that help cyclists, drivers, pedestrians and transit riders navigate our streets. It’s part of our effort to keep everyone safe as they travel in and around the city.

Seattle is recognized as one of the safest cities in the country, but there’s more work to do to reach our Vision Zero goal of ending traffic fatalities and serious injuries by 2030. We continue to improve our transportation network to make our roadways safer for all. Thank you for continuing to look out for one another, whether you’re walking, cycling, or driving.

Over the past week, the SDOT blog illustrated the concept that all pedestrian treatments at signals are not universal. We are committed to choosing the right treatment for the right place in order to have both safe and efficient operation for all transit modes. We also discussed that SDOT is working on new guidelines to help our engineers decided which treatment to use where. You may be asking yourself what treatments can we do at intersections?

Crosswalk light at Meridian Ave N and N 105th St

Below is a list we developed of different types of signal timing treatments at intersections. Some of these are stand-alone treatments and some can be combined with others. This list is not fully exhaustive as we also have an inventory of over 1100 signals where we have existing treatments that we try not to use as we revise signal timing and overall operation.

Disclaimer: This gets very transportation nerdy.

Walk Times

Slower walk speed for flashing don’t walk calculation.

The standard calculation currently uses a 3.5 feet per second walk speed which changed in 2009.

Longer walk time by request

This allows the pedestrian to push and hold the push button and request a longer walk time than usual. We’ve only tried this at one location so far Elliot and Roy.

Time of day walk times

This allows the engineer to program different walk times for different parts of the day. In some locations, like adaptive corridors, the signal chooses different cycle lengths depending on traffic volumes. In these locations programming different walk times for those cycle lengths is critical.

All-walk at Broadway and Denny

Separate Phases

All-Way Walk

This treatment programs all the walk phases to come on at the same time and is timed to allow for someone to make the diagonal crossing.

All Walk

This treatment programs all the walk phases to come on at the same time and is not timed to allow for someone to make the diagonal crossing.

Leading Pedestrian Interval

This treatment gives pedestrians a 3 to 5 second head start on compatible vehicle phases in order for the pedestrian to be fully visible in the crosswalk.

Delayed Walk

This treatment gives vehicles a 3 to 5 second head start on compatible pedestrian phases in order to clear vehicle traffic and reduce potential conflicts.

Right Turn Overlap

This treatment services right turn phases during compatible movements in order to clear vehicle traffic and reduce potential conflicts.

Turn Restrictions

This treatment limits turning by vehicles in order to reduce potential conflicts.

Protected Turns

This treatment creates separate phases for pedestrian movements and turns in order to reduce conflicts.

Leading Turns

This treatment brings up protected turns at the beginning of a cycle in order to clear vehicle traffic and reduce potential conflicts.

Lagging Turns

This treatment brings up protected turns at the end of a cycle.

Compatible Walks with Special Phase

This treatment reservices pedestrian phases during special phases like transit queue jumps or compatible turn movements.

Protected Walk

This treatment uses a flashing yellow arrow for left turns when no pedestrian is detected and a protect only turn when pedestrians are detected.

Pedestrian Overlap*

This treatment reservices pedestrian during compatible movements.

Detection Methods

Passive Detection*

This treatment detects pedestrian presence at an intersection without the pedestrian having to do anything.

Vehicle Call = Ped Call

This treatment puts in a request for a pedestrian phase any time a compatible vehicle phase is requested.

Pedestrian Recall

This treatment puts in a request for a pedestrian phase on every cycle.

Dual Coord Phase

This treatment puts in a request for all phases on every cycle.

Cycle Lengths

Lower Cycle Lengths

This treatment lowers the amount of time you have to wait between walk phases at any given crosswalk at an intersection.

Half Cycles

This treatment provides more opportunities to cross by lowering cycle lengths at minor intersections on a corridor while still providing progression for the main road at the intersection.

Late Arrival

Pedestrian Reservice*

This treatment reservices pedestrians after the green for the compatible vehicle phase has already started.

Late Call*

This treatment creates a bigger window for pedestrians to request a pedestrian phase before moving to the next phase in the cycle.

*These treatments are not currently available in our signal software but we are working with our manufacturer on prioritizing these elements. So stay tuned! Next time, we’ll discuss the pro’s and con’s of these treatments!

The simple answer: no. Not at all. Just like a doctor doesn’t prescribe stitches for a stomach ache, our SDOT traffic signal engineers don’t apply identical pedestrian treatments to all intersections. Seriously, all jokes aside, each intersection is unique, and therefore require different treatments depending a wide variety of factors. For example, is traffic flow heavy or light? Are the walkers mostly University students heading to classes throughout the day, or adults dashing to and from work? Even the environmental details surrounding the busiest times of day play a role in helping SDOT engineers determine the right crosswalk for any given intersection. Oh, and in case you didn’t know, there are a few different kinds of crosswalks:

All-way Walk

All Walk

Leading Pedestrian Intervals.

All Walk vs. All-Way Walk

That’s right, All Walk and All-way Walk should not be used interchangeably, because they are not one and the same.

Here’s the difference:

All Walks only service pedestrians in the typical crosswalks at the intersection. Example: Broadway E and E Denny Way near the Capitol Hill Station- straight across, no diagonal crossing here.

At more complicated intersections, longer signal cycles don’t play well with others. Shorter signal cycles are more user friendly in locations with heavy pedestrian travel and side street traffic because they offer more opportunities for people to cross. Hooray!

Pedestrians crossing at Broadway E and E Olive Way (Photo Credit: The Urbanist)

Both run a 70-second signal cycle

An All Walk at each intersection = 25 seconds of that 70 second cycle

An All-way Walk = 35 seconds of the 70 second cycle

Broadway/Olive is a complex intersection with lots of left turns and a heavy transit use on Olive

If there was an All Walk or an All-way Walk at Olive, here’s what one could expect:Scenario 1: Multiple blocks of gridlock in all directions because buses, bikes and cars would all be vying for the last 35 to 45 seconds of the signal cycle Scenario 2:Pedestrians arriving at the end of the walk cycle would wait 35 to 45 seconds until they had another turn to move in any direction

Instead, SDOT engineers decided to: Use a Leading Pedestrian Interval, which gives pedestrians a few extra seconds at the start of the walk cycle, making them more visible to turning traffic and still leaving about 65 seconds for other traffic

This prescribed crosswalk allows pedestrians who want to go caddy corner to have shorter wait times, because they can either walk north/south or east/west at almost all times of the cycle!

Broadway/Denny is much less complex since half of Denny is a One-way. Therefore an All-Walk was placed at this intersection. Design modelling showed that the extra ten seconds of an All-way Walk would cause backups at the intersection and force an undesirably long signal cycle.

Who knew that ten tiny little seconds could have such a major impact on on traffic? Well, SDOT traffic engineers knew, which just goes to show why crosswalks are not one size fits all.

We’ve been working with pedestrian advocates on a better understanding of the complexities of traffic signal timing in the city, ever since a local campaign called #GivePedsTheGreen started last spring. The campaign proposes removing pedestrian push buttons in all urban villages. Here’s why that’s not a good idea.

Americans with Disabilities Act (ADA)

We used to have a policy in which pedestrian push buttons were removed in areas with heavy pedestrian traffic – however, that contrasts with our obligation to provide effective communication to people with visual and/or hearing impairments wanting to cross the streets. Because of this obligation under the ADA, we strive to provide that communication using accessible pedestrian signals (APS). Deaf, hard of hearing, blind, and visually impaired pedestrians may rely on these buttons to move freely throughout the city. The signs that go with these signals are required to help that movement.

Right Treatment, Right Place

Our ongoing dialogue with pedestrian advocates prompted us to improve our guidance around pedestrian treatments at traffic signals. It’s not a matter of either having them or not having them. The fact is, we need these pedestrian buttons. But we can use them differently depending on the circumstances of each location.

Other Ways to Help Pedestrians

Traffic signal technology is constantly improving and that means there are many different treatments our signal engineers are looking at to help improve the pedestrian experience.

Passive pedestrian detection – we’re testing thermal imaging to detect pedestrians so that someday, maybe they won’t have to push buttons to be detected. This tech is similar to how vehicles, buses, and bikes are detected at signals. The challenge is that pedestrians are not as predictable as a vehicle, bus or bike in a travel lane.

Soundscapes is an amazing example of how new technology could help deaf, hard of hearing, blind, and visually impaired pedestrians navigate a city. We visited researchers at Microsoft who developed a pilot that uses a headset, smartphone, and outdoor beacons to immerse users in an audio-rich environment, to help people with vision loss move with more confidence and independence on city streets. This is a prototype for now.

Not all treatments are universal. We have a lot of different tools in our tool box and we look at the specifics of each intersection to determine the right tool to use.

A quote from a Soundscapes engineer hits home:

“We were born as a company of engineers building products for other engineers and geeks. That’s no longer the case. This notion of design empathy, or being able to build something for someone who is not like you — it’s much, much harder. You really need to adopt a perspective other than your own to pull it off.”

As an operational agency we have many different advocates who want us to create a safe and efficient system for vehicles, buses, bikes, pedestrians, and freight. We’re pretty sure that the majority of people can understand that. Our commitment will always be to constantly look for opportunities to improve. Our advocates are a huge piece of that commitment, helping us in the right direction.

Ok, the troll is actually two blocks away from this intersection, but he can still see the brand new traffic control signal our crews just installed right down the hill at N 34th St and Troll Ave N.

We also added new crosswalk markings in all directions to improve safety for all travelers – pedestrians, bikers and drivers. It’s all part of our Vision Zero plan to end traffic deaths and serious injuries on Seattle’s streets by 2030.

A big thanks to our neighbor Shanna Braga who flipped the switch and turned on the power to the new traffic control signal! “This is a great addition to the neighborhood. We’ve seen the neighborhood grow significantly in the last four years. I appreciate all the work SDOT has put into it and worked with us and the Fremont Association,” says Shanna.

“I’ll be waiting!” says the Troll.

Stay tuned for the new all-way stop just up the street at N 36th St, right in front of the Fremont Troll!

Could certain intersections in the city work better with “STOP” signs instead of traffic signals? That’s what we started looking into earlier this year. Why? Traffic signals that worked well in the past may not be working as well for the needs of our changing community.

Signal to Stop intersection implemented at University Way and NE 40th St in 2014. Collisions declined from three to zero (3-year before and 3-year after comparison).

SDOT engineers have chosen three intersections for a pilot program to see which ones might work better with “STOP” signs instead of traffic signals. These intersections are near schools that will benefit people walking, riding bikes, and driving vehicles:

SW Admiral Way and 59th Avenue SW in West Seattle

College Way N and N 95th Street in Northgate

NE 50th Street and 17th Avenue NE in University District

SW Admiral Way and 59th Ave SW

Our crews will change the traffic signal light operation from “red/yellow/green” to “red flashing” mode. They’ll also install stop signs at the intersections and cover the pedestrian signals.

NE 50th St and 17th Ave NE

People driving and riding bikes must stop at the intersection and yield the right of way to pedestrians in the crosswalk and traffic in the intersection. If you arrive at the intersection at the same time as another person driving or riding a bike, please yield the right of way to the person on the right, as required by law.

We’ll evaluate these intersections for six months to see how well the changes are for everyone who uses the intersections. We might also make more changes during this trial period, if they’re needed.

This morning wayfarers were pleasantly surprised during their morning commute across Terry Ave N and Denny Way.

The object of their morning bliss? A brand new crossing signal!

SDOT traffic engineers flipped the switch on the signal this morning around 5:45 am, and heard lots of praises from early morning runners, coffee drinkers and Seattle Times staffers, whose offices are adjacent to the intersection. SDOT will keep a close watch out for possible congestion given the close proximity to nearby signal intersection at Westlake Ave N and Denny Way, making adjustments as needed. What a difference seven seconds makes!

Our crews are just about done installing a new public art project, led by the community, for the Little Saigon neighborhood at 12th Ave S and S Jackson St, as part of our Community Crosswalks program.

According to the artist, the crosswalk represents the tale of how Vietnam was founded.

The crosswalk design has three main components: the turtle, lotus plant, and water. Each of these objects play a role in illustrating the Vietnamese American experience and culture. The turtle has been present for centuries in Vietnamese mythology and is strongly associated with luck, longevity, and perseverance. The lotus symbolizes beauty and strength in the face of adversity. The blue water gradient is a nod to the ocean that borders Vietnam and depicts a sense of adaptability, a quality that Vietnamese immigrants and refugees had to embrace in order to rebuild their lives in new countries and cultures.*

The Little Saigon community has been working on a design for these decorative crosswalks for the past year, with two goals in mind:

To contribute a cultural marker for the Vietnamese American community in Little Saigon